The present invention relates generally to imaging assemblies which include donor and receptor elements, such as used in the printing field, more particularly, to laser addressable mass transfer imaging assemblies, as well as methods of making and using the same.
In the printing field, a variety of imaging assemblies have been used for forming positive and negative images on various substrates, such as print, proofs, printing plates, films or masks. One known category of imaging assemblies is a thermal mass transfer type. Thermal mass transfer imaging includes, for instance, dye diffusion thermal transfer, wax melt, and laser ablation transfer. Generally with mass transfer imaging approaches, heat is selectively applied in an imagewise manner to a donor element of a composite donor and receptor imaging assembly for effecting transfer of preselected portions of a donor material, such as a polymer or a colorant, onto a coextensive receptor element or substrate. U.S. Pat. No. 5,256,506 describes a very successful imaging media which, in response to laser activation, effects a laser-ablation type transfer of pixels of donor material to the receptor.
In imaging these known types of mass transfer imaging media, it has been the usual practice for the donor and receptor elements to be handled separately and then joined and held together during imaging before their subsequent separation. The typical donor and receptor elements are thin and fragile and, therefore, must be handled with great care to avoid damage, such as abrasion and scratching during handling and transfer. For imaging this kind of media, the donor and receptor elements are held in uniform contact by a vacuum lamination procedure which involves holding both the donor and receptor elements together by vacuum. For instance, in laser addressable mass transfer imaging systems, such as described in U.S. Pat. Nos. 5,171,650 and 5,156,938, a receptor element is mounted on internal or external drum's of laser recorders followed by the physical overlaying an oversized donor element over the receptor element. The donor and receptor elements are usually held together by vacuum drawn through features on the drum. This process is, however, subject to certain drawbacks in terms of the possibility of dust and paper debris becoming trapped between the juxtaposed elements. The inclusion of such debris sometimes gives rise to image artifacts or defects during subsequent laser imaging. Moreover, because vacuum is applied to the sheets, there is an enhanced probability of small air bubbles becoming entrained between their interface with the consequence of non-uniform gaps being formed. The presence of such bubbles also leads to the formation of undesirable imaging artifacts.
Heretofore, several solutions have been proposed for overcoming these drawbacks and these have included rather elaborate and costly mechanical approaches, such as media web precleaning, positive air pressure in the write engine, and squeegee devices which are used to force the air from the interface of the donor and receptor elements.
Accordingly, there is a continuing desire to improve upon approaches for handling a mass transfer imaging assembly in manner which maintains its integrity, facilitates ease of handling, as well as continued usage with known imaging devices, and, importantly, allows imaging to be performed in a manner whereby the resulting images are free of undesirable image artifacts.